Media captionWhat are the "dos and don'ts" for modern business leaders when it comes to how they dress?

Watch the crowds rushing towards the trains around 5pm in any UK city and it's usually a sea of grey and navy.

The smart suits in sober neutral colours make it hard to pick anyone out amid the thronging crowds.

A suit, sometimes with a tie sometimes without, has long been the unofficial uniform for professional males.

Yet this standard corporate wear - which masks any hint of individuality - is a problem, according to British fashion designer Ozwald Boateng, the former creative director of Givenchy.

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You can wear any colour you choose if it's the right shade [for you], says Ozwald Boateng

Known for designing close-fitting, colourful suits, Mr Boateng's modern take on traditional tailoring has given him a strong following among celebrities with clients such as Will Smith and Mick Jagger.

It seems an extraordinary demand, even more so when you're being fitted for a suit by a top designer. Why on earth wouldn't they want to look their best?

"I feel a lot of them just have not got awareness of it. A lot of CEOs don't get the power image and don't get the power of their own brand that they work for."

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Ozwald Boateng is trying to shake up office wear with a modern take on men's tailoring

He believes this reticence is reflected in the person's behaviour in the job: if they're unadventurous about what they wear then they're unlikely to be pushing the company forward, he says.

"When you're a leader, you need to be heard and anything that helps focus the attention of the people who work for you is key."

Of course a fashion designer - famed for making men stand out - would say this.

Beyond the world of Instagram-obsessed celebrities and super-models, surely it should be the work that you do, not the way that you look, which drives your success?

It's certainly something we'd like to believe.

Image copyrightChristopher Ewing, ThinkstockImage caption
Regular grooming is a must, according to UBS

When Swiss bank UBS's 44-page dress code, which advised client-facing staff on everything from appropriate underwear to the importance of regular haircuts, was leaked in 2010 it was widely mocked.

The guide said a well-groomed outward appearance helped to communicate the firm's values. It prompted derision and disbelief.

UBS may have gone overboard, but there's plenty of evidence that the bank was right to think that what you wear to work matters.

Research by Karen Pine, a psychology professor at Hertfordshire University, shows that people are judged on their overall head-to-toe appearance within seconds, and clothing is a big part of that first impression.

She found that a man in an off-the-shelf suit is judged as less successful and less flexible than his counterpart who wears a tailor-made suit, for example.

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A tailor-made suit will help you appear more successful, research suggests

'Nobody's going to listen'

It's a finding that doesn't surprise Serge Brunschwig, chief operating officer of French fashion house Christian Dior, who says ultimately people remember how you look, not what you say.

"We always say that one image is worth 1,000 words. Leaders are going to use thousands and thousands of words but the way they dress should be used to enhance their speech.

"Nobody's going to listen really, so at the end what's going to stay is the appearance."

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Christian Dior's Serge Brunschwig says how you look matters more than what you say

There is also growing evidence to suggest that appearance does not just affect how a person is perceived, but even influences how they perform.

A German study which asked people to describe their character traits when they wore either formal or casual clothing, found people were more likely to describe themselves as neat and strategic when in smart attire, and as easygoing or clumsy when dressed casually.

Fanny Moizant, the co-founder of designer fashion resale site Vestiaire Collective, says wearing the right clothes for a meeting increases her confidence.

"It's about being credible according to your position but also to your industry.

"It could seem 'light' in a way but it's how you show yourself, your personality, how you interact with people, so it's all part of how you communicate."

Some of those at the top of the business world, such as Facebook founder Mark Zuckerberg, well known for his fondness of a hoodie and flip flops, have flagrantly disregarded the unofficial corporate dress code, but she says these are the exceptions.

He is someone who's so comprehensively "made it" that there's no need to stick to the rules, effectively it's a display of power, she says.

For the rest, the key is to find what suits you, but also what can help you subtly stand out.

"I like to encourage the individual. If you're wearing clothes where you're confident in them and you're enjoying them, then that will reflect in the way you treat everyone around you," says Mr Boateng.

"That radiates through who you are and your personality."

This feature is based on interviews by CEO coach and author Steve Tappin, and by series producer Neil Koenig, for the BBC's CEO Guru series.